1. Field of the Invention
The invention relates to a ski or a snowboard, with means for adjusting a cross-sectional geometry or contour which can be pre-set and varies depending on load and/or is manually variable.
2. Prior art
Document AT 007 659 U2 proposes a ski, the running properties of which can be adapted by the respective skier. To this end, at least one recess is provided in the base body of the ski for interchangeably accommodating an insert. This insert, which can preferably be inserted in the recess in a positive fit, constitutes a composite body in conjunction with the base body, which determines the bending behavior of the ski. The purpose of these interchangeably insertable inserts is primarily to influence the bending behavior of the ski in its longitudinal direction and transversely thereto. The disadvantage of this approach is that it is necessary to provide a number of different inserts to enable the bending behavior of the ski to be individually varied in the respective desired direction.
Patent specification DE 100 19 655 A1 also describes a ski, and the user of a winter sports device, in particular a ski, can adapt it shortly after purchase to the respective intended purpose and can do so reversibly. To this end, it is proposed that the width and/or the contour of the winter sports device be designed so that it can be at least partially varied. In order to achieve this objective, it is proposed, amongst other things, that the winter sports device, in particular the ski, should be made up of several individual parts as viewed in cross-section, which can be varied in terms of their relative position with respect to one another. To this end, pivot shafts and mechanical guides are proposed. Another proposed alternative is to impart a cross-section of a wave-shaped or zigzag-shaped section to the winter sports device, in particular the ski, which extends in the transverse direction, i.e. across its width, and can be shortened. The disadvantage of this approach is that the proposed designs are technically complex and do not influence the travel behavior of such skis particularly satisfactorily under standard conditions of usage.
Patent specification U.S. Pat. No. 5,301,965 A also describes a ski, the cross-sectional geometry of which can be varied by a user as required. To this end, it is proposed that the degree of transverse curvature of the running surface facing be varied. This being the case, the running surface facing is permanently joined to the ski structure at the side edges only and its central portion is forced downwards relative to the lateral control edges by means of a plurality of screws. These screws for providing a vertical adjustment with respect to the running surface facing are inserted in so-called threaded inserts anchored in the ski structure and are spaced apart from one another at a distance of approximately 2 inches along the longitudinal mid-axis of the ski. The disadvantage of this approach is that the sub-structure of the ski is subjected to high local forces when the screws are actively forced towards the running surface facing and there is therefore an increased risk of overload. Furthermore, over longer periods of use or due to intensive changes in the geometry of the ski cross-section, there is an increasing problem due to the layers of the ski structure coming apart.
Patent specification US 2005/0006875 A1 describes a ski, the cross-sectional geometry of which varies depending on load or is changed depending on load due to flexing caused by bending loads directed vertically with respect to the binding mounting portion. These cross-sectional changes occur automatically depending on how the ski flexes. To this end, at least one push rod is provided on the top face of the ski between the binding mounting portion and the ends of the ski, the relative displacement of which relative to the ski top face when the ski flexes is used to impart a concave shape to the ski bottom face in cross-section. This load-dependent deformation of the ski bottom face is caused by a plurality of force-transmitting arms mounted between the centrally extending push rod and the outer edges of the ski. Adjusting means are also proposed, by means of which the desired forward biasing action of the push rod on the transversely extending force-transmitting arms can be pre-set. Mechanisms are also provided which are able to protect against overload and define a threshold value for a maximum pushing force of the push rod. Another proposal is to provide local reductions in the thickness of the ski in the two side edge portions of the ski. The disadvantage of this is that the specified construction is mechanically complex and the overall weight of the ski is also significantly increased. Furthermore, the proposed adjusting mechanism is designed so that in spite of relatively short travel distances in the relative displacement between the push rod and the ski top face, sufficiently strong longitudinal pushing forces and transverse forces have to be produced simply to enable the side edge portions of the ski to flex downwards at all, thereby producing an essentially concave ski cross-section or a hollow neck-type running surface shape. Moreover, to an average skier using this construction which acts on the basis of load, barely any changes are experienced or perceptible as regards the traveling behavior during active use. The centrifugal forces acting on a skier's body are usually perceptible. However, these are primarily determined by the chosen travel speed and the selected radius of curvature.
Patent specification DE 101 52 438 A1 describes a snowboard, in particular a ski, the width of which can be varied along at least a part-portion of its length by means of a prizing mechanism. To achieve this, it is proposed that a continuous slot be provided in the ski starting from its rear end extending in the direction of the binding mounting portion, i.e. the ski has a slot-shaped orifice which is open towards its rear end, which is disposed coaxially with the longitudinal axis of the ski body and may be of a wedge-shaped design. This slot-type orifice in the ski is provided with an prizing mechanism for prizing apart the board body in the region of this slot. Positioning means are also proposed, by means of which the prizing means can be statically pre-set. It is also proposed that the prizing mechanism device be coupled with the binding mounting portion, in particular with the binding mounting plate, in order to obtain a load-dependent adjustment of the prizing mechanism. The disadvantage of this approach is that the slot-shaped orifice in the board body significantly reduces its strength, in particular its breaking strength, in its end portion and increases the risk of the layers of the ski coming apart due to water or similar penetrating the structure of the board body.
Patent specification U.S. Pat. No. 3,326,564 A, which is the prior art closest to the subject matter of the invention, describes a ski with a cross-sectional geometry which can be varied depending on load. The transverse or torsional strength of this ski is significantly reduced by means of a centrally extending recess or groove or by means of a plurality of recesses or grooves extending parallel with one another, disposed in the top face of the rearward portion of the ski behind the ski binding. When increased pressure occurs at the edges, in particular when a skier starts to turn in order to change direction of travel, an essentially V-shaped cross-section is imparted to this rear part-portion due to this specially designed weakening in the cross-section. This reduces the gripping hardness of the respective ski edge under load with respect to the ground underneath and results in a cross-sectional geometry which varies depending on load, thereby preventing excessive centrifugal forces during cornering using this ski. In particular, it reduces the grip of the side control edges depending on the prevailing load of the control edges as a function of the load at the control edges, which makes it easier for beginners or untrained persons to learn to ski and in particular to turn corners. At least one leaf spring may extend across the at least one groove-shaped recess, which is elastically connected to the top face of the ski with an elastic layer disposed in between. It is also proposed that a plate be provided on the top face of the ski with an elastic layer disposed in between, which is joined via laterally projecting flanges to vertically extending elongate holes and is connected to the side faces of the ski via several screw bolts extending through these elongate holes. The purpose of these plate-shaped elements on the ski top face is to produce a predefined restriction in the capacity of the ski cross-section to deform. The disadvantage of this approach is that this ski with its intrinsic travel properties does not satisfactorily cater for the individual requirements of different users. Furthermore, this ski also slips in the rear portion, especially under hard or icy conditions, which results in a sudden risk of over-rotating when cornering and the skier can easily lose control.
Patent specification WO 2006/049508 A1 describes a ski or a snowboard with a running sole which has an originally flat cross-section. This board-type gliding device has a zone or several zones within its longitudinal extension with at least one recess in its top face, and these recesses constitute a reduction in cross-section and are intended to form defined deformation zones for raising the left and/or right portion of the board relative to its cross-sectional shape. Accordingly, the lateral, outer steel edges of the board are raised relative to its central portion by means of a tension means disposed on the top face of the board and imparts an individually adjustable tensioning action transversely to the longitudinal extension of the board, which causes the side portions of the board to bend upwards relative to the portion of the board running along the center. A board of this type can only be used without problems under certain conditions, in particular if the snow on the ground underneath is relatively soft. In the case of relatively hard ground, the travel behavior of such a ski or snowboard is impaired and its control behavior is not very satisfactory.